Skydiving, sometimes called parachuting, is a sport in which participants exit an aircraft during flight, deploy a parachute to slow their descent, and thereafter land safely on the ground. Skydivers often wear helmets during these activities. The purpose of these helmets is two-fold. First, the helmet can be used to reduce the extent of a head injury should the skydiver make a hard landing or collide with another skydiver during flight. In addition, the helmet shields the skydiver's face and eyes from direct air flow during a jump.
During a jump, fog can accumulate on the lens of a skydiver's head protector, for example, due to moisture in the skydiver's breath. This fog can reduce visibility making navigation and landing difficult. During the time interval after the skydiver jumps from the aircraft and before the parachute opens, skydivers often engage in various activities in the relative wind that is established due to their velocity. This activity is sometimes referred to as ‘free fall’. During free fall, skydivers often position themselves in various attitudes relative to the wind including the so-called “head-up” attitude and the so-called “head-down” attitude. As described herein, vents can be positioned near the head protector lens to reduce fogging by allowing outside air to flow directly over the inside surface of the lens. Preferably, this air flow will be a substantially laminar flow rather than a turbulent flow.
Turbulence or turbulent flow is a flow regime characterized by chaotic and irregular flow and often includes so-called flow eddies. These flow eddies can be described as a swirling of a fluid and the associated reverse flow currents that are created when a fluid flows over or past an obstacle. On the other hand, laminar flow, which is also called streamline flow, is a flow regime in which a fluid flows in substantially parallel layers with little or no disruption between the layers. During laminar flow, flow eddies and reverse currents do not occur to any significant extent when a fluid flows over or past an obstacle. Whether a particular flow is turbulent or laminar is determined primarily as a function of fluid flow velocity and the shape of the obstacle/surface interacting with the fluid flow.
Turbulent flow during skydiving can be problematic for several reasons. This is particularly so when the turbulence is created on the surface of a head protector lens. First, it can disrupt the user's visibility with the impact of the turbulence against the skydiver's face. In addition, turbulence can create noise and vibration which is distracting, and in some cases dangerous, to the skydiver.
With the above in mind, it is an object of the present invention to provide a head protector for use in an air flow that includes vents to reduce lens fogging. It is another object of the present invention to provide a head protector having fog reducing lens vents that are sized and positioned to reduce turbulent flow on the inside surface of the lens. It is still another object of the present invention to provide a head protector for use in skydiving that improves user visibility, comfort and safety as the skydiver engages in various activities such as positioning themselves in a head-up or head-down attitude. It is yet another object of the present invention to provide a head protector for use in skydiving that is easy to use, relatively simple to manufacture, and comparatively cost effective.